x402-gated portfolio data endpoint on Base, pay $0.02 per request in USDC.
What it does
This endpoint at `/api/v1/portfolios/55` is part of the lowpaymentfee.com platform, a collection of x402-protocol pay-per-request APIs spanning data analytics, AI/ML inference, finance/Web3, and infrastructure utilities. The specific endpoint is labeled "Premium API Access" and accepts POST requests, returning JSON responses. Payment is settled on the Base network using USDC (contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) via the x402 exact-payment scheme.
The advertised maximum amount required is 20,000 base units of USDC (6 decimals), which equals $0.02 per request. The platform markets itself as having no API keys, no rate limits, and instant access — callers simply attach an X-PAYMENT header with a valid x402 payment proof. The endpoint was confirmed live, returning a proper 402 challenge.
However, the specific functionality of the `/portfolios/55` endpoint is unclear. The landing page does not list it among the documented API categories (Data & Analytics, AI & ML, Finance & Web3, Infrastructure), and no OpenAPI schema, request/response examples, or detailed documentation were found. The docs, pricing, API, and README pages all returned only a "Connect wallet" prompt with no substantive content. The endpoint's purpose — whether it returns portfolio holdings, performance data, or something else — must be inferred from the path alone and remains uncertain.
Capabilities
Use cases
- —Fetching portfolio data (likely holdings or performance) for portfolio ID 55
- —Integrating pay-per-request data access into agent workflows without API key management
- —Programmatic access to premium data behind x402 micropayment gating
Fit
Best for
- —Agents or bots that need keyless, pay-per-call API access
- —Developers experimenting with x402 protocol integrations on Base
- —Low-volume consumers who prefer per-request pricing over subscriptions
Not for
- —Users who need detailed documentation or guaranteed SLAs before integrating
- —High-volume consumers who would benefit from bulk pricing or subscriptions
- —Anyone needing non-USDC or non-Base-network payment options
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/55 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge with clear pricing, but there is no documentation, no OpenAPI schema, no request/response examples, and the specific purpose of /portfolios/55 is not described anywhere in the crawled material. This is effectively a stub listing.
Warnings
- —The specific functionality of /api/v1/portfolios/55 is undocumented — it does not appear in the site's listed API categories.
- —All documentation pages (docs, pricing, API, README) returned only 'Connect wallet' with no substantive content.
- —No OpenAPI spec, request schema, or response schema available — callers cannot know what to send or expect back.
- —The endpoint path suggests a hardcoded resource ID (55); it is unclear whether other portfolio IDs are available or what they represent.
Citations
- —The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/portfolios/55
- —USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/portfolios/55
- —Platform advertises $0.02 per request, no API keys, no rate limits, instant accesshttps://lowpaymentfee.com
- —The /portfolios/55 endpoint is not listed among the site's documented API categorieshttps://lowpaymentfee.com